Mr. Struck served as Germany’s defense minister from 2002 to 2005. While an opponent of the Iraq war, he oversaw the early years of Germany’s military engagement in ­Afghanistan, famously announcing that ‘‘German security is being defended in the Hindu Kush’’ mountains.

Chancellor Angela Merkel, who came to power in a coalition with Mr. Struck’s party in 2005, called him ‘‘a great parliamentarian’’ who strongly defended his positions but was always a reliable partner.

‘‘With his death, Germany is losing a steadfast and authentic personality, who embodied like almost no one else the country’s defense policy,’’ said Defense Minister Thomas de Maiziere. ‘‘He liked the soldiers, and they liked him.’’

Since 2010, Mr. Struck had led the Friedrich-Ebert-Stiftung, a major foundation affiliated with his party.